By Remark REF  if \(w\in W^{2,q}(\Omega )\)  all the above
quantities are finite. When \(R=1\)  the existence of \(C_1,C_2\)  is obtained in
[1]}, and in particular assumption \((4)^{\prime }\)  therein
is fulfilled as
\(\frac{1-\alpha }{2-\alpha } \le a\) 
